The present invention relates to the field of machinery and agricultural equipment, more particularly the soil-preparation machines and their constituent parts, especially the wearing parts.
The invention relates more specifically to a soil-preparation tool for a rotary harrow, to a rotary harrow equipped with such tools and to a method for manufacturing these latter.
The soil-preparation tools considered in the present application encompass in particular but not limitatively the tools for rotary harrows of the type disclosed in document EP A 0891688 in the name of the Applicant. Such tools have a body with a first upper connecting part and a second lower part forming a blade, designed to prepare the soil.
The active or working portion of this blade extends from its free lower end over a particular height corresponding to the optimum working depth of the tool. It is this working portion that is capable of and designed for being engaged and displaced in the soil to loosen the ground and break up the clods: consequently it is subjected to considerable wear, which primarily affects the active face and of course the front rim and/or edge thereof, which is the first to come into contact with the ground during use of the tool in question.
The tools of these harrows are generally mounted in pairs on rotors which turn alternately in opposite directions of rotation, from which a particular orientation of the tools results, by specific conformation of their bodies, resulting in right-hand tools and left-hand tools.
To increase the life of the tools, it is known to treat the active parts with a filler metal in the form of cladding or coating, for example to provide a coating of tungsten carbide (compare with a tool known by the designation DURAKUHN—registered trademark).
It is also known to attach elements in the form of inserts of a hard and abrasion-resistant material (for example, metal carbide) at the level of the zones subjected to intense wear, in order to form the front edge and the active adjoining faces at least of the working portion of the tool. These inserts make it possible to maintain the regularity of working of the tool for a lengthy duration (by preserving the shape of the active portion) and to increase the life of the tools.
According to a first known solution, illustrated by document EP 2445329, for example, these inserts are mounted directly on the tool body, at the level of its active position, Nevertheless, this known solution is based on a complex shape of the inserts, in particular with a nose associated with a shoulder on the rear face, and it is not optimized for application to a rotary harrow tool.
According to a second solution, already implemented by the Applicant, the inserts are mounted on an intermediate support piece that itself is integral with the tool body.
In this second solution, the inserts define a wide-angle (especially greater than 90°) angular active edge with a central edge and two active faces (double bevel), which requires elevated power during driving of the corresponding tool.